The number of Americans living with hemodialysis shot up by three times in the 1990s, to total nearly 400,000 people in 2009. Since diabetes and high blood pressure remain major chronic diseases and the top reasons for kidney failure requiring dialysis treatment, the need for long-term vascular access is expected to continue to increase.
Evaluation of extremity vessels by ultrasound is a vital component for both initial arteriovenous access for dialysis and continued monitoring of these accesses over the years of treatment. Vascular surgeons who place fistulas and other types of arteriovenous access rely on sonographers well-versed in mapping the vasculature in the access site and serial postoperative surveillance of these accesses, helping to identify complications that commonly crop up over the years. Managing a patient’s vascular access well is imperative to minimize the rate of repeat hospitalizations and frequency of additional vascular access procedures, all of which can have a huge impact on the patient’s quality of life.
Dr. John Bry, FACS, RPVI, RVT, Medical Director for Mint Medical, emphasizes the importance of good ultrasound imaging by sonographers with training and experience in this particular area. “An access surgeon optimizes their practice with the support of a skilled ultrasound technician,” Dr. Bry says. In his practice, the sonographer is asked to complete a preoperative evaluation before the placement of the venous access and a second ultrasound evaluation about a month after initial placement to confirm patency and evaluate the early evidence of fistula maturation. A final pre-dialysis ultrasound is obtained again at 10 weeks to check flow volumes, confirm fistula diameters at several levels, and to give the OK to initiate dialysis.
“In order to maintain fistula patency of the access as long as possible, it is essential to have a routine surveillance program,” says Dr. Bry. Ultrasound may be needed every three to four months to check flow velocities and volumes as well as to identify sites of stenosis at the inflow, outflow and along the length of the fistula. “The idea is to try to minimize the rate of major surgical interventions so we’re not marching from one location to another and running out of options” for access sites.
When multiple access points fail, the consequences for the patient can be dire. “These are lifelines and these patients recognize it,” Dr. Bry says. Access may move from the arms to the legs to the chest, each one less ideal than the one before as risk for infection goes up. “It is very possible for patients to run out of options. It is important to proceed methodically with the creation of dialysis accesses that are predictive of long-term patency.”
The quality of the information from the ultrasound evaluation becomes increasingly important. “It’s crucial I have the detail that allows me to deliver the best care,” Dr. Bry says. He depends on a visual or a drawing by the tech showing flow volumes measured at specific locations, or “road mapping.” Good information from the sonographer “is foundational when you consider the number of dialysis patients is increasing,” he says. “It’s remarkable how many new patients I see every week.”
While the dramatic increase in dialysis patients slowed in the 2000s, it continues to steadily rise. In 2009, there were 116,395 new kidney failure diagnoses, 571,414 people living with kidney failure and 90,118 deaths among people with end-stage renal disease. The U.S. Renal Data System projects the number of people living with kidney failure will reach 774,386 by 2020.
Of the 398,861 people on dialysis in 2009, 380,760 were on hemodialysis (95% of all dialysis patients) and 18,101 were on peritoneal dialysis (5% of all dialysis patients).
Mint Medical Education will be offering a course in vascular access for ultrasound technologists in San Francisco. Mint’s case studies also offer insight into specific venous access situations, such as this one about arteriovenous fistula creation.
–Jan Greene, Mint staff writer